1. Field of the Invention
The present invention relates to a movable lens module and an optical lens module.
2. Description of Related Art
Mobile cameras or common cameras available in the market generally have zooming and focusing functions for users to shoot scenes according to personal need. The zooming and focusing can be performed by means of the motor drive, magnetic drive, or piezoelectric material drive, and the like.
The technology of the motor drive is mature. In the motor drive mode, a step motor is mainly used to drive a lens group through transmission elements such as screws or ropes, so as to move the lens group and change the relative position between the lens groups. The step motor uses the pulse signal to excite a gear-like stator in sequence, such that the rotor rotates to drive the lens group and changes a rotation direction and a rotation speed by changing a signal form. The motor drive mode is advantageous in large driving force and stable action of the lens group, and thus the motor drive is adapted to a large lens design. However, the motor drive mode occupies a large space, and is disadvantageous for the minimization of the camera, and also has a low response speed, large power-consumption, and short lifespan. In the magnetic drive mode, a magnetic driving unit is mainly composed of a magnet and a coil element, and thus occupies less space than the motor. Moreover, the complicated transmission mechanisms are not required, so the magnetic drive mode has a faster response speed than the motor and produces less noise. However, in order to obtain large driving force, the turns of the coil must be increased, which increases the resistance and causes the power-consumption problem.
The piezoelectric material drive mode is under rapid development, which utilizes a regular vibration generated by the piezoelectric material to drive a carrier to move the lens group. The piezoelectric material drive mode is mainly classified into the electrostriction mode and travelling wave mode. The current piezoelectric material drive mode includes SIDM (Smoothly Impact Drive Mechanism) mode, for example, a driving device disclosed in U.S. Pat. No. 6,215,605. As shown in FIG. 1, the driving device 2 includes piezoelectric actuators 111, 112, driving rods 116, 117, and a guiding rod 120. The driving forces generated by the piezoelectric actuators 111, 112 are transmitted to a lens L2 and a lens L4 (movable lens) respectively through the driving rods 116, 117, such that the lenses L2, L4 move along the guiding rod 120 respectively, so as to perform the zooming and focusing actions.